The 231 does not need a firewalled throttle to produce 100% HP. The rest is there so the pilot can increase the boost as the plane goes up in the air column and the air get thinner.
5756-find out if you have an intercooler. Merlyn or no Merlyn just affects critical altitude and smooths out bootstrapping. But if you have an intercooler you want to use no more than 36" on takeoff, and if you don't have an intercooler the max MP on takeoff will be 40". The intercooler was also an aftermarket item, if you don't have a Merlyn you likely don't have an intercooler, but not necessarily so.
Hope you have a Mooney CFI who has experience in the 231. It is a bit of a different bird from any other model. Not hard to fly, just different, and it is possible to hurt the engine if you use techniques you would use with an automatic wastegate aircraft (252 or better), or an NA.
Last but not least, check your fuel flow at full throttle your first time up. It needs to be 22-24.5 gal. The engine will probably be ok if it is at least 19 or 20, but I would still get it checked and adjusted, and if it is less than that get it adjusted before you fly it.
Lots of A&P's who don't know the bird, and even some who do, don't understand the fuel flow issues and you can hurt the engine with low fuel flow and high power.
Best of luck. You will love it!
Are those procedures in the POH ?
I will look in my POH and see if it has an Intercooler tomarrow